The invention relates to a switch device for operation of a number of hydraulically operated units which are arranged in a bore hole, especially for exploration of hydrocarbons from a formation in the ground. The invention will, for example, permit surface control with one hydraulic fluid stream of a number of downhole, series-connected, individually controllable admission valves, which are integrated in a production tubing which extends down into the sea bed for use, for example, in zone-isolated, perforated and/or open production areas in an oil/gas well.
With present-day surface control of four independently operated downhole admission valves, for example, the four valves each have to be supplied with their own hydraulic control power through individual high pressure lines. This requires investment in and maintenance of expensive lines, which also have to be pulled in and coiled up on deck every time the production tubing is raised. The requirements for adequate throughway between the inner fluid-conducting pipe and the outer casing creates difficulties when lowering a plurality of such lines.
It is known that the pressure varies in the different production zones. This may be reflected in reduced production, where, for example, in a lower zone there is extremely high pressure, while the upper zone has lower pressure. The oil will then be able to travel in circular movements between the reservoir zones, with the result that it will not be extracted. The problem is solved by control/adjustment of the influx from the individual zones outside the casing.
It is further known that the different zones contain essentially different quantities of oil, gas and/or condensate, with the result that one or more zones successively produce increasing amounts of water as the zone is emptied. With current technology the oil and water-containing consistency from several zones is produced until the average proportion of mixture is approximately 90% water. At this stage the bore hole has to be closed as no longer profitable according to a cost/benefit evaluation.
If, for example, a well system is planned with six branches to six defined production zones, during the production period heterogeneous mixtures of oil/water will flow from these zones, which have been shown to produce more and more water.
The invention permits the total flow from the respective zones to be controlled by one hydraulic fluid stream from deck on the surface by activating one or more valves, which close one or more water-producing zones, with the added result that deposits of oil are forced into an adjacent advantageous zone. The zone or zones which produce undesirable amounts of water after prolonged production, and those zones which continue to produce acceptable oil concentrations are periodically registered.
By selectively shutting off the unacceptable water-producing zones in a well with, e.g., six branches, the likelihood of extending and thereby increasing the extraction of oil from a field is substantially improved. In extreme cases Be last zone of, e.g., six will product continuous amounts of oil far beyond the period when the five other zones have had to be closed. Estimates of this carried out by Rogalandsforskning amongst others indicate that the operating period of an oilfield can be extended from 3000 days to more than 5000 days, and with a progressively increasing volume.
If, for example, water injection is employed in surrounding geological formations, it will be possible to push the oil reservoirs towards the production zones in the area around the casing. If this reservoir control is employed together with the present invention, which permits regulated influx control, maximum exploitation will be achieved.
Mineral deposits which are deposited on the inside of the upstream pipe occur particularly when the water mixture in the oil reaches a certain level. The problem is reduced by facilities for controlling the water mixture, and the use of deposit-inhibiting chemical injections is also radically reduced, there being no need for such chemicals during a substantial part of the production phase.
Downhole pressure is typically around 350 bar, with a temperature of over/under 100xc2x0 C. Vertical installation depth is usually from 900 to 8000 metres, while the measured extent may be up to 6000-16000 metres. The principles can also be used for H2S and CO2 environments where the question of material choice becomes crucial for translating the principles into practical implementation.
A position meter or meters may also be inserted to indicate the degree of opening of the valve(s), thus giving the operator on the surface verification that the desired through-flow area has been achieved.
In order to obtain sequential co-operation of a number of, e.g., admission valves in the same well, an electro-hydraulic control system is currently employed, where an addressable solenoid valve only requires one fluid line from the control unit on the rig floor. The valves thus control the hydraulic power into respective valve chambers.
A method for addressing one hydraulic fluid stream by means of a sequential fluid-switching device to two or more independent or series-connected operated units, e.g. hydraulic admission valves or fluid switches, permits surface control of downhole series-connected, individually steplessly adjustable units, which are integrated in a fluid-producing pipe lowered in zone-isolated perforated and/or open production areas in an oil/gas well, without the use of lowered cables for electronic control.
In GB 2 213514 it is disclosed an apparatus for pressurized cleaning of flow conductors having a rotor which is movable relative to a cylinder by means of a zig-zag track of the and a lug of the above-mentioned type. The fluid which operates the rotor is the same fluid which flows in the suing and which is used for the cleaning purpose. No further hydraulic devices are operated by the fluid,
In GB 2 248 465 it is disclosed a valve arrangement that enables the opening and closing of a test string circulation valve and a tubing isolating valve. These valves are operated directly and mechanically by the rotor. The fluid which flows in and around the string is the same fluid with which the rotor and therefore the valves are operated.
A purpose of the invention is to provide a switch device of the type mentioned in the introduction, with which a number of hydraulic devices may be operated independently of the well fluid which is transported in the bore hole and the string.